Brain stimulation technologies using electricity are used to cure patients' diseases and to disclose functions of a brain by being applied to creatures except human beings.
Electrical stimulators include wired electrical stimulators and wireless electrical stimulators. Commercialized wireless electrical stimulators are small enough not to impose a physical burden on large-sized creatures such as chimpanzees, but are not small enough to be applied to small-sized creatures such as mice.
One of implantable electrical stimulators applied to mice that are relatively small creatures weighs about 28 g (Xu et al., 2004, Journal of neuroscience methods), but cannot be applied to mice, considering that average mouse weighs about 25 g. Therefore, an electrode implanted in the head of a mouse is connected to an external large-sized electrical stimulator using a long wire so that electrical stimulation is applied to the head of the mouse through the electrode. FIG. 1 is a view illustrating an example of such a conventional electrical stimulating device for brain stimulation in mice and small animals.
In the electrical stimulating device, the mouse needs to be trained so that a wire is connected to an electrode implanted in the head of the mouse, and the wire limits the free movement of the mouse. Occasionally, the mouse severs the wire. Further, it is difficult to experiment with several mice at the same time using the wired electrical stimulating device.
Therefore, if a small-sized electrical stimulator implantable in small creatures such as mice is developed, studies using mice can be easily conducted without the aforementioned problems. If the electrical stimulator is used for studies on higher brain functions such as sociality, remarkable studies on brain functions can be made.